Questions tagged [propeller]

Aircraft propellers are airfoils which convert rotary motion from a piston or turbine engine into thrust suitable for propelling an aircraft.

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2answers
194 views

What are the most number of propellors that a rotorcraft has been flown with?

If you had 1000 small propellors you could accelerate upwards many times faster than with 4 large propellors. What are the rotorcraft experiments with the most number of propellors ever?
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What are the main differences between scimitar and regular propellers?

I am looking to know the main differences between scimitar and regular propellers. Can somebody help me on this?
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What is autofeather for?

What is autofeather and when is it used?
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Why are commercial propeller aircraft smaller than commercial jet aircraft? [duplicate]

I've read that turbo-prop aircraft are more efficient than jet-aircraft. Browsing this Wikipedia page it looks like in general, jet airliners burn less fuel per passenger. I imagine this is due to jet ...
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Is there really anything to be gained by placing the propeller at the top of the vertical stabiliser?

I am currently designing an electrically powered RC plane with one propeller. The wingspan is c. 2.5 m and the length c. 1.6 m. Right now the plan is to put the propeller at the top of the VS where ...
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Can quadcopter-like UAVs ever get significantly quieter? Any candidate technology?

The light weight quadcopter and hexacopter UAVs that can cary say 2kg to 20kg payloads for "delivery" produce enough noise that a steady stream of pizza and book deliveries might not be so welcome in ...
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Why does the spiraling slipstream from a propeller hit the left side of the fin?

In the picture below, if the fuselage was shorter/longer, would the spiraling slipstream from a propeller hit the fin on the right side as opposed to the left? Is it a deliberate positioning if yes, ...
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Why do ground crews rotate a radial engine's propeller before a motor/cartridge start?

In footage from WWII you often see the ground crew rotating the propeller of a radial engine a number of times before the pilots start the engine. I know it's not the same as hand-starting (hand-...
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Why do most propeller-powered planes not have an autothrottle?

Why does every kind of propeller-powered plane lack an auto-throttle? No single-props no twin-props, not even turboprops like the Dash-8 Q400. To be honest, I don't know many turboprops, but if the ...
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How much could human power add to the endurance of an electric gyrocopter?

If we take a single seater electric gyrocopter like this one, could a human-powered propeller like this add to the endurance of the aircraft? The gyrocopter only needs a 32km/h forward speed to stay ...
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505 views

How can I scale down a propeller for wind tunnel testing?

I want to scale down my propeller for a wind tunnel testing. But I am unable to find any literature on it. Please give suggestions.
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How can I use electric motor data with my prop data to obtain a power available verses velocity curve?

I'm not entirely sure this is appropriate for this forum but it's worth a shot... I have propeller data ($C_T$ , $C_P$ , J , and $\eta$) and very very limited electric brushless motor data (motor ...
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What is the equation for the energy balance between turbine, compressor and propeller?

Let's consider the next turboprop arrangement: What I am looking for I am looking for an equation that involves $\dot{W}_T$, $\dot{W}_C$ and $\dot{W}_P$ (i.e. the power done by each component). This ...
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What are the pros and cons of scimitar propellers?

I know scimitar propellers are used to reduce noise, but what is their downside? There has to be one, considering most propellers don't use that shape.
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Are ducted fans more efficient?

As far as static thrust, does a shrouded/ducted propeller outperform an un-shrouded propeller? It seems that the guide blades on the bottom of the duct would allow little more thrust to be extracted ...
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How does the performance of an aircrafts propeller change with respect to distance from obstructions?

I am interested to know if there are any changes in propeller performance (thrust, efficiency) with respect to distance from obstructions such as the fuselage or wings? I am particularly looking for ...
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Do propellers have any lead/lag mechanism?

The fan blades in a fanjet are mounted loosely in a fir-tree shaped mount so they are free to lead or lag and balance themselves. The blades on fully articulated and semi-rigid helicopter rotor heads ...
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Can jet engines be used for VTOL civilian aircraft?

Why do almost all civilian VTOL aircraft existing today use propellers (or rotors) for take off and landing and not jet engines (as the Harrier does)? Is there a technical reason for this?
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How does a fan differ from a propeller?

Why is the fan in a turbofan different than a propeller in a small airplane? Why do propellers typically have 2 or 3 blades, but the fan has a lot more? And why is the fan shrouded but the propeller ...
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1answer
388 views

What is the Effect of Unsynchronized Propellers?

A long time ago, I had the privilege of flying in 4 engine turboprop airplanes in which the props were 'synched'(blades rotating in same speed) which of course is necessary for smooth thrust. However,...
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How is propeller thrust vector accurately expressed for airplanes and multirotors? [closed]

For propellers, as the airspeed increases thrust decreases. Is the airspeed component taken as a vector quantity perpendicular to the propeller? If that's true, then it's quite easy to visualize in ...
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361 views

Propeller Torque [duplicate]

We know that every rotating device generates torque . How does a single engine propeller A/C (Piper) counter-balance the torque which is being produced by nose propeller?
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Has the United States Air Force used Contra-rotating Propeller Aircraft?

I recently saw a picture of a Russian Bear(TU-95) intercepting one of our(US) military aircraft over the Pacific Ocean. Many years ago, when I flew in reconnaissance aircraft, we were frequently ...
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Which way should I rotate the propeller of a C172?

During pre-flight which direction should I be rotating the propeller of a Cessna 172 if I need to reach the alternator belt? I thought I was told "In the direction it rotates during flight"; however ...
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How far ahead of the wing should a propeller be located for a UAV? [closed]

This question is asked in context of a fixed wing, Unmanned Aerial Vehicle (UAV), with a wing span of about 5m (16ft). How far ahead of the wing leading edge should the propeller be located? The ...
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Can noise from contra-rotating propellers be reduced by having a different number of blades on each propeller?

Heads up: This came from Wikipedia's page on contra-rotating propellers and it explicitly says citation needed: However they can be very noisy ... It is also helpful if the two propellers have a ...
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Can the measured thrust of a propeller be greater than the max thrust predicted by Froude's theory?

Can the measured thrust of a propeller be greater than the maximum possible thrust predicted by Froude's Propeller Theory? Is Froude's theory reliable in practice regarding the upper limit of the ...
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Is it possible to tilt a propeller for attitude control, similarly to jet thrust vectoring?

Are there examples of propellers tilted in a controlled way to help in attitude control for pitch and yaw, adding a torque component? Tilted propeller assumption This would be similar to thrust ...
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What is the correct formula to calculate propeller efficiency?

How to calculate in the right way the efficiency of a propeller? If we know the engine power, speed of the plane and the thrust of its propeller, what is the correct method, (1) or (2), for ...
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What was the exact propeller geometry of the 1903 Wright Flyer? A modern replica failed the test T = D in a NASA wind tunnel [closed]

Full-Scale 1903 Wright Flyer failed the test Thrust = Drag in a NASA wind tunnel I have found a presentation about an extensive set of tests done in 1999 on a full scale replica of Flyer I 1903. The ...
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Looking for the correct propeller shape to create a small copter [duplicate]

I am trying to create a mini flying quadrocopter using a Raspberry Pi (mini programmable computer). So far I have hooked up the RPi to 4 motors with controls to each. I'm pretty happy with that side ...
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Rings around propellers [duplicate]

As a followup to Why do turbofan blade tips exceed the speed of sounds while prop tips should not my question is: why have rings on propellers not been used to overcome this problem? It seems from ...
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How critical is it if a pebble blows into a propeller?

How critical is it if a pebble blows into a propeller while taxiing and leaves a small abrasion in the leading edge? It wasn't noticed during flight and there was no apparent change in performance of ...
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How can an airplane fly with single propeller without rolling over? [duplicate]

I have no knowledge about aviation or mechanics or something. Recently I started a computer game 'besiege', a kind of sandbox-like game with bunch of parts to make all kinds of machinery. And I'm ...
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What are these aircraft? Seen in silhouette over Palm Springs

Screen capture on iMac, of photo posted and claimed taken 11/21/15. Palm Springs, CA
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What are the advantages of more than 4 propeller blades?

I have heard that propellers with more than four blades are not as efficient as 4 or less blades because of lower thrust which may result from interfering prop-streams. But I see the ATR-42/72 and ...
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Why should a test flight should be performed when the propellers are changed?

From this question I've learned that after a propeller change the plane should go through a test flight. Why is this?
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Are propellers obsolete? [duplicate]

Now that we have jet engines and all, is there still a use for propeller based flight (besides helicopters)? Most airlines nowadays don't use propellers, right?
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Why does this calculation show Gustave Whitehead's propellers were more than 100% efficient?

I have tried to calculate the efficiency of Gustave Whitehead's propellers using the information he provided to the American Inventor Magazine in 1902 (see the citation below). Number of propellers = ...
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Is this a good or a bad propeller?

I want to see if a propeller is bad or good for generating static thrust. This is what I know about the propeller and the engine used to turn it during a test: Engine shaft power, $P$ = 0.58 hp ...
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Why do turbofan blade tips exceed the speed of sound while prop tips should not?

It seems that the tips of the fan of a turbofan engine can and do break the sound barrier: The GE-90 has a fan diameter of 3124 mm and a rotational speed of 3475 RPM. Their circumferential velocity ...
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How much distance do I need between quadcopter propellers to avoid issues?

For a given propeller size (say 5"), what is the minimum clearance needed between propellers to ensure that not only do they not hit each other (easy to calculate), they also don't interfere too much ...
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Do quadcopter propellers break the sound barrier?

I recently bought a quadcopter and noticed every time I fly it there is this weird buzzing noise. I have heard this noise on other quadcopters around the same size as mine(4in by 4in). On an airliner ...
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What is the incidence angle of a propeller in the terminology of the Wright Brothers and how did they obtain it?

What is the angle of incidence of a propeller in the terminology of the Wright Brothers and how did they obtain it? In Feb. 1903 (see Screw Test 1903, page 8), using a 0.58 hp engine, the Wright ...
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How did Wilbur Wright create and use the formulas he mentions in his letter to Octave Chanute?

In a letter written by Wilbur Wright and addressed to Octave Chanute, dated 1903/06/18, I have found two things that I do not quite understand. Our engine develops at the brake 15.6 horse power and ...
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How is mass flow rate computed?

I have been wondering how the mass flow rate is determined by the area of the engine air intake surface and the incoming speed of the air. In still air, it is understandable that a stationary engine ...
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What are these circles around the propeller?

(Source: www.airliners.net) These circles I believe are the wing tip vortex formed by the propeller tips or is it just due to the rotation of the propeller. How does this occur?
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What happened to the blades in this picture?

Here is the picture Source:(brians-travels.com) This looks like a photoshopped picture, but I believe it isn't. Is this some kind of strange occurrence that occurs only with the human eye? The ...
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Would a headwind result in a faster propeller rpm?

A few weeks ago I did an experiment with a model aircraft that has a motorized propeller. I turned on the propeller and it turned at a constant speed. Then I turned on a desk fan and put it in front ...
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What is downwash on a wing and how does it form? [duplicate]

This is a subject I have been very confused with lately about thrust coming from downwash on a propeller and helicopter, but to understand how the downwash increases thrust is to know how it forms and ...